How to simulate Caps Lock keystroke with CGEventCreateKeyboardEvent in OS X

Has anyone had any luck simulating Caps Lock keystroke with CGEventCreateKeyboardEvent on OS X? Basically I have tried alphabetic character and alphanumeric character okay but Caps Lock. Hopefully, I would like to simulate Caps Lock keystroke to trun on/off the LED. I don't know what problem is for my test code. Has anyone had experinces for this?

#include <stdio.h>
#include <ApplicationServices/ApplicationServices.h>

main()
{
    bool wasCapsLockDown = CGEventSourceKeyState(kCGEventSourceStateHIDSystemState, 57);
    if (wasCapsLockDown)
        printf("On\n");
    else
        printf("Off\n");
    ProcessSerialNumber psn;
    GetFrontProcess(&psn);
    CGEventSourceRef source = CGEventSourceCreate(kCGEventSourceStateHIDSystemState);//CGEventSourceCreate(kCGEventSourceStateCombinedSessionState);
    CGEventRef CapsLockDown = CGEventCreateKeyboardEvent(source, (CGKeyCode)57, true);
    //CGEventFlags modifiers = 0;
    //modifiers |= kCGEventFlagMaskAlphaShift;
    //CGEventSetFlags(CapsLockDown, modifiers);
    CGEventRef CapsLockUp = CGEventCreateKeyboardEvent(source, (CGKeyCode)57, false);

    // simulate capslock down
    CGEventPost(kCGHIDEventTap, CapsLockDown);
    // simulate capslock up
    CGEventPost(kCGHIDEventTap, CapsLockUp);

    //CGEventPost(kCGAnnotatedSessionEventTap, CapsLockDown); /* doesn't work */
    //CGEventPost(kCGAnnotatedSessionEventTap, CapsLockUp);

    //CGEventPost(kCGSessionEventTap, CapsLockDown); /* doesn't work */
    //CGEventPost(kCGSessionEventTap, CapsLockUp);

    //CGEventPostToPSN(&psn, CapsLockDo开发者_如何学编程wn); /* doesn't work */
    //CGEventPostToPSN(&psn, CapsLockUp);

    CFRelease(CapsLockUp);
    CFRelease(CapsLockDown);
    CFRelease(source);
}

Compile with below command

    gcc test.c -framework ApplicationServices

Do you need to actually toggle the caps lock state, or is merely turning the LED on/off sufficient? If it's just the LEDs, there's some sample code at:

https://github.com/mikeash/mikeash.com-svn/blob/master/CPUFlash/keyboard_leds.c

Note that it doesn't involve CGEvent at all -- it uses IOKit magic to mess with the keyboard LEDs directly.

Haha! This might just be a classic.. Your code exits because it was really able to do anything at all. Add some sleep(seconds)'s here and there. Also try putting a small delay (usleep(microseconds)) in between the down and up events.